Photographic support

ABSTRACT

On the back of a polyolefin laminated paper, a support for photographic light sensitive material, a coating layer composed of colloidal alumina is applied in order to prevent the paper from blistering during microwave heating.

O United States Patent 1 [111 3,884,692 Minagawa May 20, 1975 [54]PHOTOGRAPHIC SUPPORT 3.l69,865 2/1965 Wood 96/85 3,352 682 11/1967Harris et a1. 5 96/95 [75] Inventor: Nobuhrko Mlnagawa, Shrzuoka,3,520,242 7/1970 Kemp et 96/85 Japan 3,525,621 8/1970 Miller 96/853,743,537 7/1973 Honjo et a1. 96/85 [73] Assgnee' 5" i' 3,769.02010/1973 Verburg." 96/85 anagawa 3,793,029 2/1974 Parker 96/85 [22]Filed: Mar. 13, 1973 2 1 App] 340 790 Primary ExaminerMary F. KelleyAttorney, Agent, or FirmSughrue, Rothwell, Mion, Zinn & Macpeak [30]Foreign Application Priority Data Mar. 14, 1972 Japan 47-2588] [57]ABSTRACT U-S. CL R o th ba k of a polyolefin laminated paper, a sup-[51] hit. Cl G036 l/86 port for photographic light Sensitive material, acoat [58] Fleld of Search 96/85, 87 ing layer composed f colloidalalumina is applied in order to prevent the paper from blistering duringmi- [56] References Cited crowave heating UNITED STATES PATENTS 7 72,647,835 8/1953 Weaver 96/85 14 Clams 2 Dmwmg 1 PHOTOG RAPl-IIC SUPPORTBACKGROUND OF Tl-IE'INVENTION l. Field of the Invention v The presentinvention relates to an improved'support for photographic papers.

2. Description of the Prior Art It has been a recent tendency thephotographic lightsensitive material art to promote developmentprocessing. As a part of this trend, water-proof photographic paper hasbeen developed and put into use. With a water-proof photographic papercomprising a paper support coated on both sides with a hydrophobicpolyolefin resin the time required for washing and drying afterdevelopment processing has been greatly shortened because the supportdoes not absorb development processing solution. Such papers have,however, required the employment of a different method of drying ascompared to conventional papers.

Heretofore, the drying of photographic papers subjected to developmentprocessing has usually been conducted by bringing the emulsion-coatedsurface of a non-dried photographic paper into contact with a heated,smooth metallic plate to thereby evaporate from the back of thephotographic paper moisture contained in both the emulsion layer and thesupport paper, i.e., by so-calledferrotype drying.

However, in a water-proof photographic paper ferrotype drying cannotnecessarily be said to be the optimal drying method because'the supportdoes not have permeability to water vapor. Rather, there is a tendencyto use drying methods based on hot air, infrared rays or the like. Onedrying method of extremely high efficiency, microwave heating, hasrecently been considered by the art. In microwave heating, thetime'required for the temperature to rise due to thermal conduction isso small as to be negligible because microwave heating causes internalheat generation in the substance heated. In addition, microwaveenergy'is absorbed most efficiently by water molecules. Therefore,microwave heating can be said to be extremely advantageous as a methodfor drying photographic papers.

Where drying with microwaves is applied to a waterproof photographicpaper, water contained in the emulsion layer absorbs microwave energy togenerate heat which contributes to the drying of the emulsion layer,while water originally contained in a slight amount in the paperconstituting the support similarly functions as a heat-producing bodyand promotes the drying of the emulsion layer. For these reasons, themicrowave drying of water-proof photographic paper will probably berapidly put into use in the near'future.

SUMMARY OF THE INVENTION The inventors have discovered, however, thatthe microwave drying of water-proof papers has two serious pletely driedwith microwaves, water-,drops remain undried on the back of the support.

2. In microwave drying blisters are liable to occur on the'polyolefinfilm coated on the back of water-proof photographic papers. .k

The inventors will not herein venture to discuss in detail the cause ofsuch blisters, but, roughly speaking, the cause is consideredto be asfollows; water contained in a paper support is vaporized by themicrowave heating, resulting in an increase in-the pressure inside thesupport, which leads to the deformation of the polyolefin laminated onthe back of the support, the polyolefin being in a softened state.

Water drops described in item (1) above hinder the effeciency of theheating process, which is the strongest merit of microwave heating,'andthe blisters described in item (2) above spoil the appearance of thephotographic paper to such an extent that the commercial value of thephotographic papers is completely lost. Therefore, in putting microwavedrying of water-proof photographic papers into use, it is necessary toremove the above-described two defects. v

As a result of extensive investigations to solve these problems, theinventors reached the present invention, i.e., the above defects areovercome with a photographic support comprising a polyolefin-laminatedpaper having on its back a coating layer of colloidal alumina.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THBiNyENTiThere is no particularrestriction onthe kind and thickness of the paperused in the invention; but paper for photographic uses, art paper,etc.having smooth surfaces and weighing g/m to 300 g/m is preferred. I

The polyolefins used in this invention are polyethylene, polypropyleneand mixtures thereof in any proportion.

The polyethylene and polypropylene used may beslected from any of thosein' the prior art, and their equivalents, which have been used to formpolyolefin laminated papers, and the improved results of the presentinvention are achieved with all of such materials. Preferably thepolyethylene has a melt index of about 1 to about 30 and a density ofabout 0.91 to about 0.97, while the polypropylene has a melt index ofabout 0.1 to about 20 and a density of about 0.88 to about 0.91. Theseranges are not limitative, however, and are merely to serve as aguideline to one skilled in the art.

The polyolefin can be used in various thicknesses, but at thicknessesmuch less than .1 [J. insufficient water-proofing may be achieved, whileno need exists to use a thickness much greater than 100 u.

Polyolefin-laminated papers are usually prepared by casting moltenpolyolefin onto arunning paper base, i.e., by the socalled extrusioncoating method, whereby both sides of the paper are laminated or coatedwith polyolefin. The surface of the polyolefin-laminated paper to whichan emulsion will be applied can be a glossy surface, matted surface,silk-like surface, etc. depending upon the use thereof, whereas the backof the laminated paper is usually non-glossy.

The colloidal alumina used in the invention is fibrous alumina (hydrate)l mu to 1,000 mu, preferably 10 my. to 100 mu, in size. Processes forproducing the same and the properties thereof are explained in detail inJapanese Pat. Nos. 20150/64, 14292/65 and 570/66.

A process for providing a coating layer of colloidal alumina on the backof a photographic support comprising a polyolefin-coated paper isspecifically described below.

Colloidal alumina is diluted with water or an organic solvent misciblewith water to prepare a coating solution. The concentration of colloidalalumina in the coating solution is set taking into consideration thecoating amount required, the viscosity of the solution suitable for thecoating method employed and the like. However, usually, theconcentration of solid ingredients, i.e., alumina, is in the range offrom 1 g to 50 g per 1 liter of the coating solution. In addition, itdoes not destroy the benefits of the present invention to add variousresins, dyes, matting agents such as silica, inorganic substances, andthe like to the colloidal alumina coating solution in order to improveother characteristics such as the coefficient of friction, writingproperty and color. For instance, the additive resins can be water ororganic solvent soluble resins such as polyvinyl acetate, polyvinylalcohol, gelatin, nitrocellulose, etc., the dyes can be any dye which isnot decomposed at process conditions, the matting agents can be selectedfrom those commonly used in the art, e.g., clay, silica, etc. andappropriate inorganic substances are water soluble compounds such assodium chloride, sodium sulfate, potassium nitrate, etc.

The thus obtained coating solution containing colloidal alumina isapplied to the back of a polyolefinlaminated paper by any usual coatingmethod such as roll coating, bar coating, gravure coating, etc.

It is sufficient to apply the colloidal alumina in an amount of not morethan 1 g per 1 m of a support (exclusive of other components), generallyin an amount greater than 0.05 g/m Amounts greater than 1 g/m can .beused, if desired, but no significant increase in improved results isobtained. The 0.05 g/m is a more important parameter as the upper figureis nonlimiting.

Activation of the polyolefin surface prior to the coating of thecolloidal alumina is not particularly required, but, where resin iscontained in the coating solution or where especially strong adhesionbetween the coating layer and the polyolefin surface is required, it ispreferred to activate the polyolefinlaminated surface by coronadischarge or the like, e.g., corona discharge as described in BritishPat. Specification Nos. 771,234; 715,914; 870,224; 989,377; 971,058;1,005,631; 1,019,664; 1,043,703; 1,134,211 and 1,136,902; U.S. Pat. Nos.3,411,908; 3,53,922; 3,549,406; 3,520,242; and 3,076,720; mechanicalroughening as described in British Pat. Specification No. 1,076,410;flame treatment as described in U.S. Pat. Nos. 3,072,483; 3,153,683;3,255,034; 3,375,126; 3,431,135; 3,590,107, etc. and in British Pat.Specification No. 1,010,649; elution as described in U.S. Pat. No.2,846,727; ozone treatment as described in U.S. Pat. No. 2,715,075;radio frequency electromagnetic treatment as described in British Pat.Specification No. l,294,l 16; andchromic acid treatment as described inJapanese Pat. No. 38-22148.

The characteristics required of the thus obtained backcoating layer are:it should not be delaminated during the production or use of thephotographic lightsensitive material; it should exert no harmfulinfluence on a photographic emulsion; it should not cause sticking oradhesion to the surface emulsion layer under high humidity conditions;and it should prevent the formation of above-described'water drops andblisters. The colloidal alumina coating layer in accordance with theinvention satisfies all of the above-described requirements.

Furthermore, in addition to the intended microwave drying capability,the colloidal alumina also provides the substantial merits that apasting property (ability to adhere materials to the substrate byadhesives and a writing property, which a noncoated support does notpossess, are obtained.

The method employed in this specification to rate the microwave dryingcapability of water-proof papers is as follows: a water-proof paper issubjected to a development processing by an usual development processingas shown in FIG. 1, and the non-dried, processes waterproof paper isdried by means of a microwave heating apparatus shown in FIG. 2.

In FIG. 1, numeral 1 denotes a water-proof photographic paper wound as aroll and 2 denotes a development processing bath.

It is to be specifically noted that no criticality is attached to thedevelopment processing of the present invention and any developing knownto the art for the emulsion involved (any photographic emulsion may, ofcourse, be used) can be used.

In FIG. 2, numeral 3 denotes a microwave generator, 4 denotes awaveguide, and 5 denotes a water-proof photographic paper which has beensubjected to development processing. In FIGS. 1 and 2, the water-proofphotographic paper runs in the direction indicated by the arrow.

The microwave drying capability was rated by examining the relationshipbetween both the oscillation power and the velocity of the microwavestraveling through the waveguide and the state of the dried surface ofthe water-proof photographic paper.

The microwaves can be of any type known to the art which provide asufficient drying effect. Preferably, and this range includescommercially available microwave sources, the microwaves have afrequency of about 900 MHZ to 2,500 MHz.

The present invention will now be illustrated in greater detail byseveral non-limiting examples of preferred embodiments of the invention.

In all examples the microwaves used were of a frequency of 900 MHz to2,500 MHz.

In Examples 1 3 the polyolefins were coated by extrusion coating. InExample 4 the paper base was covered by preformed polypropylene films onboth sides.

EXAMPLE 1 Both sides of a photographic paper weighing 180 g/m werelaminated with polyethylene (density 0.92, melting index 2.6), atathickness of 30 p. to prepare support A. A colloidal alumina solutionhaving the following composition was applied to the back of support A toprepare support B.

ALUMINA SOL-* (colloidal alumina 'made by Nissan Chemicals Industries,Ltd.)

-Continued Methanol 2 liter (the composition of ALUMINA SOL-100 is it)wtfk M 2 wL'Z HCl and 88 wt. water. size is in the range I my, to llKIllmp.)

The amount of solid ingredients coated to prepare support B was 1.0 g/mTo each of support A and support B was applied the same emulsion forcolor photographic paper to thereby prepare two water-proof colorphotographic papers.

The thus obtained water-proof color photographic papers were exposed andsubjected to development processing using a standard commercial colordeveloper and the apparatus shown in FIG. 1 and subsequently dried bymeans of the microwave drier shown in FIG. 2. The relationship betweenthe running rate of the water-proof photographic paper being dried andthe state of the dried surface was examined while set- -ContinuedPotassium bromide 4 2 Water I l After developing and water-washing, thepaper was fixed in the following solution for 4 min.

Sodium thiosulfate (anhydride) Sodium sulfite (anhydride) Water 350g lOgll Thiourea 60 g ting the power of the microwave generator at 1.5 KW.Potassium bromide 30 g The results shown in Table l were obtained.Hydrochlorlc acld 30 ml 2-amino-3-hydroxyphenadine 0.0 ll Table 1 WaterI I Support State of dried Running rate r surface m/ iin. The paper waswashed with water and then sub ected 1 2 4 to silver-bleaching in thefollowing solution. A At the back 0 0 e e Blister G O O O B At the backO O O O Blister O O O O Crystalline copper sulfate 100 g Hydrochloricacid In this and the following examples, O in the line At the Back meansthat the back of the paper is dried, while 6 means that the back of thepaper is still wet or water drops remain on the back. Also, O in theline Blister means that no blisters formed on the back of the paper,while e means that blisters formed on the back of the paper.

As is clear from Table l, in the water-proof photographic paper wheresupport A is used the drying conditions where no blisters formed on theback of the paper and complete drying is attained is narrow, whereas inthe water-proof photographic paper wherein support B is used the rangeof drying conditions is wide, the drying velocity is large and, inaddition, blisters on the back of the paper do not occur. Preparation ofColor Photographic Emulsion Used 0.2 g of magenta coupler,4-(3',5-dibutyloxycarbonylphenyl azo )-5-amino-l-naphthol, was dissolvedin 2 ml of tricresylphosphate. The solution was added to a 10% by weightaqueous gelatin solution containing 2 ml of a 10 weight aqueous sodiumalkyl benzene sulfonate solution and then the mixture was subjected tohomogenizing to emulsify. Six g of the resulting emulsion was mixed with20 g of a silver chlorobromide photographic emulsion containing about 30g of silver bromide per 1 kg of the emulsion to provide the finalemulsion.

Development Processing Used After exposing, the color papers weredeveloped in the solutions having the following compositions for 10minutes;

Sodium carbonate ml Water 1 l The paper was then washed with water,fixed in the fixing bath, washed again and then dried.

By the above treatment, a magenta image having completely bleachedhalide portions was obtained.

This material was favorable for the magenta component image of amalti-colored photosensitive material.

EXAMPLE 2 Both sides of a high quality paper weighing g/m were laminatedwith polyethylene (density 0.96, melt index 15) at a thickness of 30 uto prepare support C. On the other hand, the back of support C wassubjected to corona discharge treatment at a discharge output of 4 KWand a discharge treating velocity of 100 m/min., and subsequently coatedwith a solution having the following composition to prepare support D.

ALUMlNA SOL-I00, as in Example I 2 kg MOVINYL DMlH*( polyvinyl acetateemulsion, made by Hoechst 0.01 kg Gosei K.K.)

Water 8 liter (39 wt.% polyvinyl acetate and 70 wt.% water) The amountof solid ingredients coated to prepare support D was 0.3 g/m To each ofsupport C and support D was applied the same emulsion for black-andwhitephotographic paper to produce water-proof photographic papers. The thusobtained waterproof photographic papers were subjected to developmentprocessing and dried using the same apparatus as was used in Example I.In this example, the power of the microwave generator was set at 3.0 KW,and the relationship between the running rate of the water-proof photo-ALUMINA SOL-200*(colloidal alumina made by Nissan Chemicals Industries,Ltd.)

. 7 8 graphic paper in the drier and the state of dried surface Cominuedwas examined. The results shown in Table 2 were obtamed gSNOWTEX-O**(colloidal silica made 2 kg by Nissan Chemicals Industries,Ltd.)

Table 2 Methanol 10 liters I 5 pp 8mm of dried Running rate 2; 2 wt.'7racetic acid and 88 wt)? water, size is in the range l mu Surface' 1 "3""4 mm Wm SiO anJ so wt water) C back 8 g g g 0 The amount of colloidalalumina coated to prepare D A! the back O O O support F was 0.4 g/m Toeach of support E and sup- 3 O O O 0 port F was applied the'sameemulsion for color photo- V v graphic paper as was used in Example 1 toproduce wa- As is evident from Table 2, in the water-proof paperter'proof P Q f P P p whlch' after pwherein support C is used there isobserved either reent processing in the apparatus of FIG. 1 using ademaining water drops on the back or the formation of Veloper as Example1, were mlcmwaves' blisters on the back under any drying conditions,which in the Same manner as in EXamPle In this mpl virtually makes'microwave drying impossible. In conthe power of the microwave generatorwas 2.0 KW. trast, in the water-proof photographic paper wherein Therelationship between the drying velocity and the pp D 15 used, the Stateof the (med Surface 15 g state of the dried surface was examined. Theresults obeven when the running rate of the water-proof phototamed areShown in Table graphic paper, i.e., drying velocity, is as large as 5m/min. Thus, the effects of coating the alumina sol to T the back ofsupport are seen to be highly beneficial. 2 Composition of Black & WhitePhotographic Emulsion 5 ppo Sta e of d ied Running rate Used surface(m/min.)

Silver chlorobromide containing E $2 1 back 3 g g g 50 mole of silverbromide 28 g (particle size: 0.6 micron) 30 F A, the back 0 o o -OGelatin 120 g BIlSIel' O O O O 6 weight aqueous saponin solution 2.5 cc5 weight aqueous chromium alum 5 cc solution I 6 weight aqueousformaldehyde 10 cc From Table 3 it is seen that the effects of coatlngthe $212? to 1000 cc back of the support in accordance with the presentinvention are evident. The composition of the developer used EXAMPLE 4 wh I h l A I 5 40 Polypropylene films 20 p. inthickness (density 0.91) tt golgieumysaulililsgnfil;grige su ae) 450 g were laminated on bothsides of a paper for photo- Hydroquinone l g-8 g graph c use weighing200 g/m to prepare support G. 132%: l hydrate) 210 Z Separately, asolution having the following composition Water I 10 3000 cc was appliedto the back of support G to prepare support l-l.

' EXAMPLE 3 The surface of a high quality art paper weighing 300 g/m waslaminated with polyethylene (density 0.92 I ALUMINA SOL-200 2 l g/cm",melt index 25) and the back thereof was lami- Methaml 200 mm nated witha mixture of polyethylene (same as above) (0.8 part byweight) andpolypropylene (0.2 part by g weight) of (density 092 glcma melt index 4)each The amount of collczldal alumina coated to prepare layer of athickness of 30 u, to prepare support E. Sepav PP F g/ To each of511M301t G and P rately, the back of support E was subjected to coronaport H wasapplied the same emulsion for color photodischarge treatmentat a corona discharge treating vegraphic paper as was used in Example 1to produce walocity of 100 m/min. and subsequently coated with a t fphotographic papers. The resulting photo-' s having thefollowmg smf 2 Pgraphic papers were subjected to-a development prosupport F.The'strength of the corona discharge treatessing by means 20f thedevelopment processing-111% Kw per Z' P- expresseclijas chine shown inFIG. 1 using a developer as inExample decimal power. S t b Smfce t ggiggl, and then the nondried, water-proof photographic pa- S 5 charge Y izit i g g at: e perswere dried by passing them through a microwave pose og drier as shown in FIG. 2. In this example, the state of the driedsurface was examined by changing the power of the microwave oscillationwhile fixing the running rate of the paper in the microwave drier to belm/min.

Table 4 Support State of dried Power of oscillation surface (KW) At thehack Q Q 0 O Blister O O O Q H At the back O O O O Blister O O O O FromTable 4, it is seen that coating of alumina on the back of the supportprevents the formation of blisters and, in addition, the back can bedried with micro waves of low energy.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:

l. A photographic light-sensitive material comprising a. a support whichcomprises a polyolefin-laminated paper having on its back a coatinglayer composed of fibrous colloidal alumina (hydrate), and

b. a silver halide emulsion layer on the side of said support oppositethe alumina coated side.

2. A photographic light-sensitive material as claimed in claim 1,wherein both surfaces of said paper are polyolefin coated.

3. A photographic light-sensitive material as claimed in claim 1,wherein the thickness of a polyolefin layer on said paper is from to 100,u.

4. A photographic light-sensitive material as claimed in claim 1,wherein said polyolefin is polyethylene, polypropylene or ,a mixture ofpolyethylene and polypropylene.

5. A photographic light-sensitive material as claimed in claim 1,wherein the size of the alumina is from 1 to 1,000 mu.

6. A photographic light-sensitive material as claimed in claim 1,wherein the coating amount of alumina is 10 more than 0.05 g/m 7. Aphotographic light-sensitive material as claimed in claim 5, wherein thesize of the alumina is from 10 12. A photographic light-sensitivematerial as claimed in claim 1, wherein the polyolefin ispolyethylenepolypropylene mixture.

13. A photographic light-sensitive material as claimed in claim 4,wherein the polyethylene has a density of about 0.91 to about 0.97 and amelt index of about 1 to about 30 and the polypropylene has a density ofabout 0.88 to about 0.91 and a melt index of about 0.1 to about 20.

14. A photographic light-sensitive material as claimed in claim 4,wherein:

a. the paper has a weight of g/m to 300 g/m and is coated on both sideswith a polyolefin layer; b. a polyolefin layer is 10 to 100 ,a thick; c.the alumina has a size of 1 my. to 1,000 mu; d. the alumina is presentin a layer consisting essentially of alumina in an amount of 0.05 to lg/m esthe polyethylene has a density of from about 0.91 to about 0.97and a melt index of from about 1 to about 30; and f. the polypropylenehas a density of from about 0.88 to about 0.91 and a melt index of fromabout 0.1

to about 20.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 884,692

DATED May 20, I975 INVENTO R(S) Nobuhiko MINAGA WA It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below: 4 O

IN THE SPECIFICATION:

Column 3, line 53 delete "3, 53, 922" and insert 3, 253, 922

Q Signed and Scaled this twenty-first D 3.) Of October 1975 [SEAL]Attest:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufParenrsand Trademarks

1. A PHOTOGRAPHIC LIGHT-SENSITIVE MATERIAL COMPRISING A. A SUPPORT WHICHCOMPRISES A POLYOLEFIN-LAMINATED PAPER HAVING ON ITS BACK A COATINGLAYER COMPOSED OF FIBROUS COLLOIDAL ALUMINA (HYDRATE), AND
 2. Aphotographic light-sensitive material as claimed in claim 1, whereinboth surfaces of said paper are polyolefin coated.
 3. A photographiclight-sensitive material as claimed in claim 1, wherein the thickness ofa polyolefin layer on said paper is from 10 to 100 Mu .
 4. Aphotographic light-sensitive material as claimed in claim 1, whereinsaid polyolefin is polyethylene, polypropylene or a mixture ofpolyethylene and polypropylene.
 5. A photographic light-sensitivematerial as claimed in claim 1, wherein the size of the alumina is from1 to 1,000 m Mu .
 6. A photographic light-sensitive material as claimedin claim 1, wherein the coating amount of alumina is more than 0.05g/m2.
 7. A photographic light-sensitive material as claimed in claim 5,wherein the size of the alumina is from 10 to 100 m Mu .
 8. Aphotographic light-sensitive material as claimed in claim 6, wherein thecoating amount of alumina is less than 1 g/m2.
 9. A photographiclight-sensitive material as claimed in claim 1, wherein the paper has aweight of 100 g/m2 to 300 g/m2.
 10. A photographic light-sensitivematerial as claimed in claim 1, wherein the support polyolefin ispolyethylene.
 11. A photographic light-sensitive material as claimed inclaim 1, wherein the polyolefin is polypropylene.
 12. A photographiclight-sensitive material as claimed in claim 1, wherein the polyolefinis polyethylenepolypropylene mixture.
 13. A photographic light-sensitivematerial as claimed in claim 4, wherein the polyethylene has a densityof about 0.91 to about 0.97 and a melt index of about 1 to about 30 andthe polypropyLene has a density of about 0.88 to about 0.91 and a meltindex of about 0.1 to about
 20. 14. A photographic light-sensitivematerial as claimed in claim 4, wherein: a. the paper has a weight of100 g/m2 to 300 g/m2 and is coated on both sides with a polyolefinlayer; b. a polyolefin layer is 10 to 100 Mu thick; c. the alumina has asize of 1 m Mu to 1,000 m Mu ; d. the alumina is present in a layerconsisting essentially of alumina in an amount of 0.05 to 1 g/m2; e. thepolyethylene has a density of from about 0.91 to about 0.97 and a meltindex of from about 1 to about 30; and f. the polypropylene has adensity of from about 0.88 to about 0.91 and a melt index of from about0.1 to about 20.